MAX8727ETB+TG104 Maxim Integrated Products, MAX8727ETB+TG104 Datasheet - Page 8

• Manufacturer Part Number: MAX8727ETB+TG104
• Description: IC DC/DC CONV TFT-LCD 10-TDFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8727ETB+TG104

• Applications: Converter, TFT, LCD
• Voltage - Input: 2.6 ~ 5.5 V
• Number Of Outputs: 1
• Voltage - Output: 2.6 ~ 24 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX8727 can be programmed for soft-start upon
power-up with an external capacitor. When the shutdown
pin is taken high, the soft-start capacitor (C
ately charged to 0.4V. Then the capacitor is charged at a
constant current of 4.5µA (typ). During this time, the SS
voltage directly controls the peak inductor current, allow-
ing 0A at V
The maximum load current is available after the soft-start
is completed. When the SHDN pin is taken low, the soft-
start capacitor is discharged to ground.
The MAX8727’s frequency can be user selected to
operate at either 640kHz or 1.2MHz. Connect FREQ to
GND for 640kHz operation. For a 1.2MHz switching fre-
quency, connect FREQ to IN. This allows the use of
small, minimum-height external components while
maintaining low output noise. FREQ has an internal
pulldown, allowing the user the option of leaving FREQ
unconnected for 640kHz operation.
TFT-LCD Step-Up DC-DC Converter
Table 1. Component List
Table 2. Component Suppliers
8
DESIGNATION
Murata
Sanyo
Sumida
Taiyo Yuden
Toshiba
C2, C7, C8
_______________________________________________________________________________________
C1
D1
L1
SUPPLIER
SS
= 0.4V to the full current limit at V
10µF ±10%, 6.3V X5R ceramic capacitor
(0805)
Murata GRM21BR60J106K
Taiyo Yuden JMK212BJ106KD
4.7µF±20%, 25V X7R ceramic capacitors
(1206)
Murata GRM31CR71E475M
3A, 30V Schottky diode (M-Flat)
Toshiba CMS02
3.6µH ±30% power inductor
Sumida CDRH6D26-3R6NC
Frequency Selection
DESCRIPTION
770-436-1300
619-661-4143
847-545-6700
800-348-2496
949-455-2000
PHONE
SS
Soft-Start
) is immedi-
SS
= 1.5V.
The MAX8727 shuts down to reduce the supply current
to 0.1µA when SHDN is low. In this mode, the internal
reference, error amplifier, comparators, and biasing cir-
cuitry turn off, and the n-channel MOSFET is turned off.
The step-up regulator’s output is connected to IN by
the external inductor and rectifier diode.
Step-up regulators using the MAX8727 can be
designed by performing simple calculations for a first
iteration. All designs should be prototyped and tested
prior to production. Table 1 provides a list of power
components for the typical applications circuit. Table 2
lists component suppliers.
External-component-value choice is primarily dictated
by the output voltage and the maximum load current,
as well as maximum and minimum input voltages.
Begin by selecting an inductor value. Once L is known,
choose the diode and capacitors.
The minimum inductance value, peak current rating, and
series resistance are factors to consider when selecting
the inductor. These factors influence the converter’s effi-
ciency, maximum output load capability, transient-
response time, and output voltage ripple. Physical size
and cost are also important factors to be considered.
The maximum output current, input voltage, output volt-
age, and switching frequency determine the inductor
value. Very high inductance values minimize the cur-
rent ripple and therefore reduce the peak current,
which decreases core losses in the inductor and I
losses in the entire power path. However, large induc-
tor values also require more energy storage and more
turns of wire, which increase physical size and can
increase I
ues decrease the physical size but increase the current
ripple and peak current. Finding the best inductor
involves choosing the best compromise between circuit
efficiency, inductor size and cost.
770-436-3030
619-661-1055
847-545-6720
847-925-0899
949-859-3963
2
FAX
R losses in the inductor. Low inductance val-
Applications Information
www.murata.com
www.sanyovideo.com
www.sumida.com
www.t-yuden.com
www.toshiba.com/taec
Inductor Selection
WEBSITE
Shutdown
2
R